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Space is trying to kill you. There’s no atmosphere, temperatures that would freeze you solid; it’s completely hostile to life. But one of the biggest risks to astronauts visiting the Moon might be solar storms. These are storms of protons and electrons blasted from the Sun and accelerated to near light speed. An unprotected astronaut could receive a lethal dose of radiation from a single sun storm.
The Sun is a superheated ball of plasma, and the constant flow and movement of this plasma creates a strong magnetic field. Over time the magnetic field lines can get twisted up and poke out of the surface of the Sun, like twisted rubber bands. These magnetic field lines can snap into a different configuration, releasing a tremendous amount of energy. We see this energy release as a solar flare on the Sun. The largest flares release X-ray radiation and instantly accelerate a cloud of protons and electrons to nearly the speed of light. These can be blasted towards the Earth as a sun storm or a proton storm.
When a powerful flare explodes on the Sun, the light takes just 8 minutes to reach Earth, and the accelerated particles arrive a few minutes or hours later. We’re protected on the surface of the Earth by the magnetosphere, which channels the particles away from the surface to the Earth’s poles. This is why we see the beautiful auroras. Even astronauts orbiting the Earth are safe from the storm of particles.
But astronauts on the Moon, or traveling to Mars could be killed if they get caught unprotected by a sun storm fired directly at them. NASA is working on a warning system, that will give astronauts a few minutes to move to a shielded part of their spaceship. A little bit of lead shielding, and even water will help reduce an astronaut’s exposure to this radiation. They’ll be able to hide out in the shielded section of the ship until the storm has passed and the risk is over.
We’ve written several articles about the Sun for Universe Today. Here’s an article about how there isn’t going to be a killer solar flare in 2012, and here’s an article about a real time solar storm warning system.
We’ve also recorded several episodes of Astronomy Cast about the Sun. Listen here, Episode 30: The Sun, Spots and All.